Mechanical pencil



Oct. 5, 1937. R. BACK MECHANICAL PENCIL Filed March 25, 1935 fwe/if 1 Ebbe/ Back.,

f L Z M lllllllllllllllllllll lllllllllllllllllllll Patented Oct.. 5,1937 I f UNIT-EDsTATl-:s

PATENT OFFICE 7 2,095,091 MECHANICAL PENCIL Robert Back, Chicago, n1., assigner to The wam Company, Chicago, Ill., a corporation of Delaware y Application March 25, 1935, Serial No. 12,814 y 11 Claims.v (C1. 1z0-1s) long lead sticks (e. g., four inches) although its utility is not limited to pencils of that particular characteristic.

Another object of the inventionk is the provision of improved construction for a.v mechanical pencil of the kind above specified which permits the length of the lead stick in the feeding mechanism to be ascertained immediately by visual inspection and without special manipulation of the parts for that purpose. f i

Another object of the invention is the provision of improved construction for a mechanical pencil of the type specified which ailords a magazine for storage of a, plurality of long lead sticks and effectively protects them4 against breakage, yet permits them to be removed with ease for purpose of reloading the feeding4 mechanism.

Yet another object is the provision of an im-l proved construction for a mechanical pencil of the type specied which is eil'ective to safeguard the operating parts against strain or distortion incident to normal use and operation of the pencil, and which is adapted to safeguard long lead sticks against breakage within the feeding mechanism. n v

Other objects include the provisiony of improved construction of various parts for purpose of obtaining certainty and accuracy in their operation, and reducing their cost.

Other and further objects will be pointed out or indicated hereinafter or willbe apparent to one skilled in the art upon an understanding of the invention or its employment in use.

For purpose of aiding in` an explanation of the invention, I show in the accompanying drawing forming a part oi' Vthis specification, and hereinafter describe, `one form in which it may beembodied. It is to be, understood, however, that this is presented merely for purpose of illustration and hence is not to be interpreted in any fashion calculated to limit the appended claims short of the true and most comprehensive scope of the invention in theA art.

In said drawing,

Fig. :1 isla broken longitudinal section of a form of pencil embodying the present invention;

Fig. 2 is a part elevational viewv of the lower end of the pencil, shown on considerably larger scale;

Fig.`3 is a cross sectionon substantially line 33ofFig.1;

Fig. 4 is a cross Section 0l! Substantially line 4-4 of Fig. 1;

Fig. 5 is a side view of the lead-holding clutch or traveler;

Fig. 6 is alower end view of the pencil; and

Fig. 7 is a fragmentary perspective view ofthek upper end portion of the lead ejecting plunger,

illustrating a `modiiied construction.

The nature "of the invention Will be ascertained most quickly from a consideration of this illustrative embodiment, which will now be de` scribed. Y y

The pencil includes a. tubular barrel III which is @made of transparent material. In the form illustrated this barrel is of primarily square cross-sectional form with beveled or rounded Q corners. Fixedly mounted in the lower' end of the barrel I0 is a bushing or collar II whichv holds a screw-like or helical tubular member I2,

of the bushing.

The lower end portion of the `barrel-is ta` I pered downwardly, and a tapered tip member I4 Vis formed to nt flush against the terminaly edge of the barrel. This Vtip member is provided with an axial bore. which, at its upper portion, is of a size to hold, with a tightpressed fit, a lead guide tube I5, said bore at 'the lower n end of the tip being reduced in size and formed to accommodate `the contemplated lead stick withV a close sliding fit. As seen in Fig. 6, this terf'v minal portion of the tip bore is of primarily square contour with rounded'or beveled corners.

The lead guide tube I5 is of a diameter adapt-` ing it to be received freely within the Vhelical tubular member I2, and the two extend throughout substantially the entire length of the barrel. The lead guide tube is slotted longitudinally throughout its full length above the tip member I4, said slot being designatedby the reference numeral I 6. The lower end of the bushing II projects slightly from the lower end of the barrel and fits into a. depression in the upper end of the tip member I4, lwhere it rides in contact with a packing washer I1.

The upper end portion of the guide tube I5V extends a short distance above .the upper end of the helical member I2, and the latter, adjacent its upper end, is provided with a notch I2b. A stop member I8 is provided, `same being in the form of a flat washer, which fits closely about the guide tube I5 and is formed vwith a depending lug I8a which fits Within the notch I2b, said :n lug extending longitudinally of the helical member across the upper end portion vof the helical the collar I9, so as to hold the collar and the stop member I8 on the tube. The construction provides a centering connection for the helical member and lead guide tube, holding them against relative longitudinal movement, but permitting rotation of the lead guide tube within the helical member,'the collar I9 rotating on thel stop member I8.

In the upper portion of the barrel is inserted a spacing member which has a vtop portion that covers the vupper end of the leadguide Vtube and helical` member, and depending leg portions 2| which engage the barrel'walls andA the helical member on four sides vand hold the helicalmember centered in the barrel (see Fig.

'3). vThe peripheral contour of theY top portion 28 corresponds to that of the leg portions as shown inFlg. 3, so that spaces areaiforded for reception of four lead sticks L within the barrel between said leg portions. The .upper end of the barrel is closedby a screw-seated plug 22 Y which supports an eraser anda removable eraserprotecting cap 24.'

Within the lead guide tube` is operably mounted thelead carrier, which is shownin sectional elevation in Fig. 1, and at a diierent angle and on v anenlarged scale in'Fig. 5. This lead carrier c omprises a hollow member 26 and a plunger 2".y The hollow portion is made of a sheet formed up into n vso a tube, the lowerfend being somewhat contracted to form a `resilient clutch 26d. A The sheethas projecting ears which are bent up against each otherand theirfmarginsrwoverlapped to formy an outstanding rigid lug 26h. The outer overlapped portions "of the -ears provide smooth uninterrupted surfaces onlthe sides of the lug'toward the ends of theucar'rier, for riding on the helical ymargini-,of the helical member. lAbovethis lug 1' thetube Iisformed with a longitudinallyy extending lslot/ or opening `28c'which terminates short of the upper end of the tube. 'The lug 26h i'sof suchsize' as to extend through and ride freely in the longitudinal `slot it of the lead @guide tube and in the helical slot' or grooveoi the helical member, as seen in Fig. 2.` The clutch portion'26a is of such size as to receiveV and resiliently grasp the contemplatedlead stick.

'me piunger'n nts, sudamy within4 the hougw member-26 Vand is `adapted'to reciprocate longic tudinallytherein y'for a distance corresponding approldmat'elyto thelength ofthe opening 26e.V

, Atk its lower end the plunger Vhas a cylindrical head 21a vwhich slidablyfilts the bore of the memportion 27e which e'xtends,outwardly beyond the' at vguide portion 2lb and is of such size as to extend into and fit freely within the helical groove het, anydvat its upper end it has a laterally extending flatvguide portion 2lb adapted to ex" tend through the slot 28c and t slidably in the slot I6 of the lead guide tube. It also has a lug or slot of the helical member.v From the outer end of the lug 21oextends an indicator element 21d, of `arcuate form corresponding to the spiral o'f the helical slot in thel helical member. The plunger is inserted in the hollow member 26 at the'uppervend thereof, before the parts of the latl ter are closed together. .f

As disposed 1n the lead guide tube and helical {membenthe carrier lug 28h and the propeller lug 21e are' spaced apart longitudinally the distance ofk one full turn of the helix. The tip mem- Y ber'isprovided with an index marking 28 which is'alignedwith the longitudinal slot of the lead guide tube. 1 f y A manner of'mounting the indicator element on the lead electing plunger is illustrated inFig.

v moval of the closure 22. i.

veating of the indicator.

The stop member I8a provides an abutment for 7. Here the plunger or lead ejector 21 is provided With a lateral groove 30 of approximately the width of the lug 21o and the indicator element is formed of a thin strip 3| of material of a contrasting color and is seated in. thegroove 30,

the material oi' lthe plunger adjacentrthe groove 1 and/or the materialy of the said strip being swaged so as to secure the strip yin place vin the groove. Thev end portion of the strip is bent laterally to form theA indicator element 21d. 'I'he indicator element is of shape and width such as to permit it to travel in the slot of the helical member and the lug 2lc and guide'portlon 2`|by form shoulders for riding upon the margins of adjacent helixes and for abutting the ends of the opening 26 and preventing -the indicator element from becoming dislodged from its position-onthe.plunger.-

With the parts assembled as above described,`

the pencil affords a magazine adapted to-hold fourlead sticks each almost aslong as the barrel. .These occupy the corner portions of the barrel and are spaced apart by the khelical member and by the legs 2|, and will run out ofthe magazinewhenvthe pencil is invertedafter rel The lead carrier is caused to kmove in either direction longitudinally in thelead guide tubey by rotationlof the tip relative .tothe barrel in the appropriate' direction'. When the carrier lug2'8b v reaches 4the lower end ofpthe slot I6, further downward movement of" the member 26 is thereby prevented and said lug may revolve in the annular space below the V.lower end of the helical member, .whereupon further relativerotation of the tip and barrel will cause the plunger rto be fed downwardly withinthe member 26, and elect any remaining portion of `the leady stick from the clutch portion and out ofthe tip..

The pencil isloaded, after vthe carrier has been` i retracted part way or all the way, by inserting the lead stick through the lowervend ofthe tip and seating itsupper end portions within the clutch',v memberinthe propeller having been re.`

tracted, to so accommodate the leadl stick, by reverse rotation of the barrel relative to the tip incident to which'retraction ofthe plungerthe feeding back of the lead; carrier lug 2Gb into the lower endA of the helical 'slot is accomplished.

With the pencil thus loaded,` the lead stick may be propelled or'projected from the tip to the tion, or the lead stick maybe vretracted by rotation of the barrel relative to the tip in the reverse or counterclockwise direction.V

The lengthpf the 1ead 'stick within the feedingVK 50 length desired andswhendesired, byL rotation of .Y l the barrel relativetothe tip in av clockwise direc-l mechanism may be immediatelylascertained at n l 'any time by observation of theV position ofthe indicator` 21d through the transparent barrel. To`

facilitate such observation, the indicator 21d is finished in a color contrasting to that of the helical member. The index 28 facilitates the loy i the plunger lug'21c when the lead carrier reaches its upper limit of travel, and prevents the helical member beingY stressed or compressed longitudi- -nally by forcible effort toward further counter- 70. the relatively flexible y slender form but having a large magazine capacity.

What I claim is:

l. In a mechanical pencil having a relatively rotatable tip and barrel, a helical member secured to the barrel at its lower end and provided with a helical slot, a longitudinally slotted lead guide tube rotatable in the helical member and connected at its lower end to the tip, a lead carrier movable longitudinally in the lead guide tube and having a projection riding in the slot of the latter and in said helical slot, and a stop member rotatably mounted on the lead guide tube at the upper end of the helical member and having a portion extending longitudinally of the helical member across said helical slot at the upper end thereof to provide an arresting abutment for said projection of the lead carrier.

2'. In a mechanical pencil, in combination, a hollow barrel having a transparent wall, lead propelling mechanism operably mounted in the barrel and including a tubular member having a helical slot therein and a lead carrier movable rotatably and longitudinally therein, and an indicator carried by said lead carrier for movement in the slot of the tubular member, said indicator presenting toward the barrel a surface contrasting in appearance with that of the tubular member and being visible through the transparent wall of the barrel.

3. In a mechanical pencil, in combination, a hollowfbar'rel having a transparent wall, lead propelling mechanism operably mounted in said barrel and including a lead carrier movable longitudinally of the barrel, said lead carrier being adapted to position a lead stick, and a con-4., spicuous indicator within the barrel and movable longitudinally with the lead carrier and visible 'through the transparent wall of the barrel for the purpose described.

4. In a mechanical pencil, a tubular lead carrier made of a sheet of resilient material formed into substantially cylindrical shape, the meeting margins of the sheet having projections extending outwardly thereon and having marginal portions overlapped to provide a projecting lug pre- 'senting smooth uninterrupted surfaces on the sides toward the ends of the carrier.

5. Ina mechanical pencil, in combination, a tubular barrel, a helical member positioned axially therein, a bushing securing said helical member to the barrel at its lower end, a longitudinally slotted tube rotatably iitted within the helical member, an annular stop member encompassing said tube and abutting the upper end of the helical member, said stop member having a portion interengaged with the helical member and extending across the slot thereof, said tube being provided with means for preventing movement of said stop member away from the helical member.

6. In a mechanical pencil, in combination, a tubular barrel, `a relatively rotatable tip member at the lower end of the barrel, a tubular helical member mounted within the barrel and secured thereto at its lower end, a slotted lead guide tube aillxed to the tip member and tting rotatably within the helical member, a lead carrier slidably tting in the lead guide tube and movable longitudinally thereof by rotation of said tube relative to the helical member, and an annular member rotatably `mounted on the upper portion of the lead guide tube above the helical member, said annular member and helical member having cooperating interengaging means serving as a stop for the lead carrier at the upper end portion of the helical member.

7. In a mechanical pencil, in combination, a tubular barrel, a bushing secured in and projecting from the lower end of the barrel, a rotatable tip riding on the projecting end of the bushing, a

lead guide tube secured to the tip and extending axially through the bushing and within the barrel, a helically slotted member encompassing the lead guide tube and having its lower end received in the bushing and engaged therewith by a slot and pin connection whichlimits downward movement of the helically slotted member relative to the bushing, and a stop member mounted on the upper end portion of the lead guide tube abutting the upper end of the helically slotted member said stop member and helically slotted member having interengaging means intercepting the erating to form a stift" projecting lug, marginal` portions of said ears being bent laterally and overlapped one across the other,'said laterally bent portions beingl arranged for camming cooperation with margins of the helical slot of the propelling member.

9. A mechanical pencil comprising, in combination, a tubular-barrel having a bore of 'generally polygonal cross-sectional form, a generally cylindrical lead-feeding element disposed.l axially in the bore of the barrel and secured to the barrel at its lower end, said cylindrical element cooperating with the barrel to form the walls of leadreceiving spaces located at the corner portions of the barrel bore and extending substantially the entire length thereof, and a spacing member seated in the upper end of the barrel and engaging the upper end portion of the cylindrical member to center it in the bore, said spacing member affording passages for insertion of lead sticks into the lead-receiving spaces, the spacing of said cylindrical member relative to the barrel wall being such as to maintain lead sticks therein spaced apart from one another.

10. In a mechanical pencil, a tubular lead car-1' rier made of a sheet of resilient material formed into a substantially cylindrical shape, the meeting margins of the sheet having projections ex-I tending outwardly thereon, said projections having their radial 'margins overlapped so that the projections mutually support each other against longitudinal thrust.

11. In a mechanical pencil, in combination, a barrel having a transparent wall portion, lead propelling mechanism operably mounted in the barrel and including a longitudinally movable lead positioning element, and an indicator movable in the barrel with the lead positioning element and 

